Four Low-Dimensional Cobalt(II) Coordination Polymers Based on a New Isophthalic Acid Derivative: Syntheses, Crystal Structures, and Properties

A isophthalic acid derivative, 5-(4′-methylphenyl)­isophthalic acid (CH3C6H4-H2ip), has been prepared. Reaction of CH3C6H4-H2ip with Co­(Ac)2·4H2O and four N-donor ancillary ligands gave four new coordination polymers, {[Co­(CH3C6H4-ip)­(bip)]·2H2O}n (1), {[Co2(CH3C6H4-ip)2(bib)]·H2O}n (2), {[Co­(CH3C6H4-ip)­(bpe)0.5(H2O)]·H2O}n (3), {[Co­(CH3C6H4-ip) (bipy)0.5]}n (4), [bip =1, 5-bis­(imidazol)­pentane, bib = 1, 4-bis­(imidazol)­butane, bpe = 1, 2-bi­(4-pyridyl)­ethene, bipy = 2, 2′-bipyridyl]. Complexes 1–4 were structurally characterized by elemental analysis, infrared spectra (IR), and X-ray single-crystal diffraction. These complexes all display low-dimensional features. Complex 1 exhibits an extended polythreaded network based on two-dimensional (2D) layers that are connected by CH3C6H4-ip and bip ligands. Complex 2 shows a 2D layer containing dinuclear paddle-wheel [Co2(CO2)4] secondary building units (SBUs). Complex 3 possesses a 2D layer and further stacks via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. Complex 4 shows a one-dimensional linear chain bridged by CH3C6H4-ip. These results suggest that both CH3C6H4-ip and N-donor coligands have a significant effect on the final structures. Variable-temperature magnetic susceptibility measurements reveal the existence of antiferromagnetic interactions in 2 and ferromagnetic interactions in 3, respectively.